One object of this invention is to provide a fast optical beam steerer with no mechanical moving parts such as oscillating mirrors, and to use the beam steerer alone or in combination with other beam steerers in near-eye displays or other display, control or communications applications.
In this disclosure, “beam steerer” refers to any device that redirects the direction of propagation of electromagnetic radiation in a continuously time-varying fashion. That is, for purposes of this disclosure, a device that is inherently non-continuous such as a sequence of switchable prisms or diffraction gratings would not be considered a beam steerer, but a variable-index prism or a continuously variable-focus lens would be considered a beam steerer. Although this disclosure will usually use the term “light” for convenience to refer to electromagnetic radiation, it should be understood that the term is intended to include visible, ultraviolet, infra-red, deep infra-red, terahertz, microwave, and other such electromagnetic radiation. Similarly, such terms as “wavelength of light” are intended to refer generally to a referenced property of electromagnetic radiation (i.e., wavelength). Accordingly, the term “beam steerer” refers generally to any continuously variable optical element, including for example traveling lenses, variable prisms, variable focal length lenses, deformable mirrors, oscillating mirrors, spatial phase modulators, and so on.
In the prior art, there are many different kinds of beam steerers implemented, including:
Acousto-optic Bragg cells
Acousto-optic pulsed traveling lenses
Acousto-optic phase modulators
Variable electro-optic prisms
Variable focus liquid crystal lenses
Liquid crystal spatial phase modulators
Liquid crystal variable focus mirrors
Kerr cells
Deformable mirrors
Also in the prior art, there are various switched optical devices such as H-PDLC switchable holograms and POLICRYPS switchable gratings; and the prior art also includes electro-optically variable diffraction efficiency gratings.